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Energy needs after converting a chest freezer to a refrigerator

 
pollinator
Posts: 280
Location: Nevada
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I would like to put a 3.5 cu. ft chest freezer in my van and use it as a refrigerator. Can someone give me an idea of how much electricity it is going to use every day? Assume that it is 75% full all the time and is only opened 4 times per day. I have seen estimates on many websites that show how to do this conversion but never for anything this small.
 
gardener
Posts: 1935
Location: Grand Valley of Colorado's Western Slope
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Hi Tom, what a great idea.

I have no idea how much electricity will be needed, or how to calculate the projected use, but a few variables are still needed: the amount of insulation, and what the ambient temperature is in the van. The electricity is going to be used to maintain a difference in temperature between the inside and the outside of the freezer, through a insulating material. So, you'll need some idea of the material.

Where will the compressor be in relation to the inside of the freezer, and how efficiently does the compressor work. And now that my mind is running down this pathway, also, where will the heat be liberated? Will you have the ability to dump the heat (from both sources) outside the van? Are you going to insulate the van itself, to maintain a cooler environment outside the frige?

And one more, is this a self defrosting freezer? They have heating elements behind the inner surface of the compartment, and they cycle heat through to melt and drain the frost, then run the compressor to recover the cold lost by the use of the heater.

For now, most appliances are not that well designed. They just use power to make up for bad design. Sigh.

I guess one way to figure it out would be to just build it, hook it up and then measure your use, and then make modifications to get a lower usage.

Thekla
 
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It really depends on how new/efficient the freezer is. Older freezers might use triple the electricity of newer models with better insulation and better compressors.

If you actually have it, or one like it...you can plug it into a Kill-a-watt meter and it will measure the watt-hours, and then you'd know.

 
Tom Connolly
pollinator
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Thanks! That is an interesting amount of information, which brings up another point. I was thinking of cutting a hole in the rear area of the van, inserting a steel box into the hole and then putting the chest into the hole. This way the fridge only sticks up about 24", low enough to actually put a mattress on top. It seems that I need to keep some air space around it ..back to the drawing board!
 
Thekla McDaniels
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Location: Grand Valley of Colorado's Western Slope
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What about making the steel box big enough to include some air space, and designing in the appropriate venting? it might be cooler "under" the van than in it. Or if you live somewhere the pavement gets really hot, and radiates a significant amount of heat upwards, insulate the bottom of the box against the heat form the bottom.

It surely is an interesting project you are planning.
 
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